Film cartridge

ABSTRACT

The take-up spindle of a super-8 format film cartridge is maintained in position by friction means. Rewinding of the spindle is accomplished by overcoming the resistance of the friction means. The take-up spindle has cams on its surface and the friction means includes a friction ring mounted in the cartridge and surrounding the take-up spindle having two resilient tongues.

ilnited States Patent Keiner et a1.

Sept. 4, 1973 FILM CARTRIDGE Inventors: Heinz Keiner, Oberndorf; HelmutRichter, Braunfels; Wilhelm Schafer, Wetzlar; Willi Goldberg, Steindorf,all of Germany Ernst Leitz G.m.b.H., Wetzlar, Germany Filed: Aug. 31,1970 Appl. No.: 68,308

Assignee:

Foreign Application Priority Data Sept. 13, 1969 Germany P 19 46 536.2

[1.8. Cl. 242/194, 352/72 lnt. Cl G03b 1/04, G1 lb 15/32 Field of Search242/194, 197-200,

[56] References Cited UNITED STATES PATENTS 3,037,719 6/1962 Behmann242/711 3,398,912 8/1968 Weggeland 3,415,599 12/1968 Winkler et a1.3,286,945 11/1966 Steisslinger 242/712 Primary ExaminerLeonard D.Christian Attorney-Krafi't and Wells 5 7 ABSTRACT The take-up spindle ofa super-8 format film cartridge is maintained in position by frictionmeans. Rewinding of the spindle is accomplished by overcoming theresistance of the friction means. The take-up spindle has cams on itssurface and the friction means includes a friction ring mounted in thecartridge and surrounding the take-up spindle having two resilienttongues.

2 Claims, 7 Drawing Figures PATENTEB SE? 4 I975 SHEET 1 0f 2 FILMCARTRIDGE BACKGROUND OF THE INVENTION 1. Field of the Invention Theinvention relates to cartridges for super-8 format film; moreparticularly the invention pertains to super- 8 format film cartridgescapable of being readily rewound.

2. Description of the Prior Art In the conventional standardizedcartridge wherein movie films in the so-called super8 format aremarketed by various film manufacturers, the take-up spindle of the filmcartridge is surrounded by a locking ring which prevents reverserotation of the spindle. Therefore, the spindle can be turned only inthe direction by which it winds the film thereupon. The blocking of thereverse rotation is necessary in order to prevent film already woundupon the spindle from unwinding and loosening when the cartridge isremoved from the camera with only partially exposed film. In such asituation, the shaft on the camera side is disengaged from the couplingclaw of the cartridge. Thus, the take-up spindle is free to movebackwards under the tension of the film. This would result in thereeling up of the uppermost layers of the film if no special blockingmeans against reverse rotation were provided.

This blocking of the reverse rotation exhibits the disadvantage that itis basically impossible to effect lap dissolves with super-8 film. As isknown, the method of effecting lap dissolve includes the steps of slowlyclosing the shutter at the end of a scene and stopping the camera, thentransporting the footage on which the shutter closing operation wasrecorded back inside the camera, and finally recording the beginning ofthe new scene, at a gradually opened shutter, on the backwound,previously exposed strip of film. However, in case of the super-8cartridges, due to the blockage of the reverse rotation of the take-upspindle, a reverse transport of the film is basically impossible. Lapdissolves therefore cannot be effected. Thus, there exists a problem offinding means making it possible to produce lap dissolves when usingsuper-8 cartridges.

SUMMARY OF THE INVENTION According to the present invention, thisproblem of making lap dissolves is solved by providing means so that thetake-up spindle of the cartridges is subjected to friction, and so thatthe spindle can be turned back by overcoming this friction.

The friction can preferably be produced by a spring element, for examplea leaf spring, effective between the take-up spindle and the cartridgehousing. The element can be fixedly arranged at the cartridge housingand exert pressure on the take-up spindle, but it can also be fixedlymounted to the take-up spindle and frictionally contact awall of thehousing.

By this arrangement of the invention, the posed problem has been solved.The previously known blockage of the take-up spindle against reverserotation, effected by the mating of parts, is overcome, for it is quitereadily possible to turn the take-up spindle backwards against thefrictional force, with the required amount of strength, so that a returntransport of the film by the force of the drive motor and thus also lapdissolves are then made possible. Yet, a loosening of the uppermostlayers of the film from the film reel on the take-up spindle is stillprevented because tensioning of the film is insufficient to overcomethis friction.

In a further embodiment of the invention, the friction effective betweenthe take-up spindle and the cartridge housing is less during forwardrotation than during reverse rotation, so that the motor of the camera,during the forward rotation normally taking place, is burdened by aslittle additional resistance as possible.

According to the present invention, this can be achieved in three ways:

Firstly, it is possible to insert, in place of the locking ring arrangedin the commercially available cartridges, a friction ring extendingaround the take-up spindle, the bore of which friction ring is definedby two substantially semicircular curve paths, the centers of which aremutually displaced in the direction of the ends of the semicircles,wherein the branches of the two curve paths in the proximity of thecenters are clearcut and undercut and form two resilient tongues, andwherein the end of each tongue facing the center is beveled at an angleof about 45 so that the curve path facing the cams attached to thetake-up spindle during the forward rotation of the spindle forms anobtuse angle with the rotational path of the cams, whereas the curvepath facing the cams during reverse rotation forms an acute angle withthe rotational path of the cams.

Thus, this special embodiment presumes that the take-up spindle isprovided with the same cams as exhibited also by the take-up spindle inthe cartridges according to the state of the art. The cams flatlycontact, during forward movement, the outwardly yielding tongues, whichlatter are readily resilient and offer hardly any resistance against therotation of the cams. During reverse movement, the cams meet the steeplybeveled tip, and it is possible in this case to further turn the take-upspindle, the only difference being that substantially more force mustnow be exerted for this purpose. This force can easily be supplied bythe drive motor in reverse gear, making a backward transport of the filmpossible. However, sufficient force cannot be supplied by the tensioningof the film, so that the loosening of the upper film layers of the reelis still prevented. The friction ring can also be conventionallyarranged to be reciprocating, so that no resistance is exerted by thefriction ring against the forward movement. In this embodiment, theresilient tongues are arranged at the level of the lateral displacementdirection.

Secondly, the locking ring can be retained in the cartridges and cancontinue to constitute the conventional blocking means in combinationwith the cams of the take-up spindle. In this case, according to theinvention, the take-up spindle is in contact with the blocking means byway of a friction coupling. For example, the hub of the take-up spindlecan be surrounded by a sleeve having a longitudinal slot and beingresiliently clampedto the hub. The sleeve also carries the cams whichcooperate with the locking ring, and when the camera is switched toreverse movement, the sleeve with the cams adheres to the locking ring,but yet a backwind of the film is possible, namely by overcoming thefriction between the sleeve and the hub. 0n the other hand, however, thetension on the film windings is not large enough to overcome thisfriction, so that the blocking effect of the locking ring remains ineffect with respect to the winding up of the film.

In place of the slotted sleeve, it is also possible to put a closedsleeve over the hub; this sleeve can be connected with other springelements resting on the takeup spindle and producing a frictionconnection between the sleeve and the spindle.

Thirdly, the different friction in case of forward movement and in caseof reverse movement can also be produced by removing the locking ring ofthe cartridge and slipping a loop spring over the bearing pin whichcarries the take-up spindle, an end of the spring being fixedly attachedto the hub of the spindle The coil spring is wound in such a manner thatit is opened during forward movement, whereas it is tightened duringreverse movement. The same success is achieved by attaching one end ofthe spring to the cartridge housing and placing the spring in acorresponding manner over the hub of the take-up spindle.

DESCRIPTION OF THE DRAWINGS In the drawings, the invention is explainedin greater detail with reference to several embodiments, to wit:

FIG. 1 is a schematic top view of a film cartridge with means to preventreverse rotation according to the prior art;

FIG. 2 is a schematic top view of a film cartridge with friction springmeans according to the first embodiment of the invention;

FIG. 3 is a top view on an enlarged scale of a friction ring which,according to a second embodiment of the invention, is inserted in thecartridge in place of the locking ring;

FIG. 4 is a schematic top view of a friction ring according to a secondembodiment of the invention, with the spindle inserted in the forwardwinding position;

FIG. 5 is a schematic top view of a friction ring according to a secondembodiment of the invention, with the spindle inserted, in the reversewinding position;

FIG. 6 is a view in cross section through a cartridge wherein thetake-up spindle, according to a third embodiment of the invention, issurrounded by a closed sleeve;

FIG. 7 is a top view of the spring ring employed in the embodimentaccording to FIG. 6;

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 there is shown acartridge housing 1 oriented with the take-up side facing the observer.The side of the cartridge has been removed. In the center, the take-upspindle 2 is rotatably mounted; this spindle is illustrated in acut-away fashion, in order to better make visible the parts essentialfor its function. The spindle 2 is surrounded by a locking ring 3, thelatter being mounted in a partition of the cartridge housing so as to bereadily displaceable laterally.

The bore of the ring 3 is formed by two approximatelycircular-arc-shaped curve paths 3a, 3b, extending eccentrically withrespect to the center of the ring and passing over into each other attwo radial edges. Three cams 2a, 2b, 2c, of the take-up spindle 2cooperate with the curve paths in such a manner that the cams, upon arotation of the clockwise direction, always displace the ring from oneside to the other, so that the spindle can freely rotate in thisdirection. However, upon a rotation in the counterclockwise direction,one of the three cams 2a, 2b, 2c, meets the most proximate radial edge,at which it is caught. Consequently, the rotation in thecounterclockwise direction is blocked. This backwind blockageillustrated in FIG. 1 represents the state of the art from which theinvention starts.

In FIG. 2, a first embodiment of the invention is illustrated,eliminating the disadvantage of this backwind blockage, namely theimpossiblity of effecting lap dissolves, and yet providing safetyagainst a loosening of the upper film windings from the take-up spindle.In this embodiment, the hub 2 of the take-up spindle is subjected to theforce of a friction spring 4 pressing on the hub 2' and braking thelatter. The locking ring 3 is not employed. The friction of the spring 4can readily be overcome by the motor of the camera, so that it is alsopossible to conduct a backwind of the take-up spindle. However, thefriction cannot be overcome by the tension of the film windings, so thatan inadvertent loosening of the uppermost film windings is impossible.

The further embodiments all start with the idea that the take-up spindleshould not be subjected to any friction, if possible, during the forwardmovement, in order to prevent additional load on the motor of thecamera. For this purpose, FIG. 3 for example, shows a friction ring 5which is inserted in the cartridge in place of the locking ring, inaccordance with the invention. The friction ring exhibits at its innerdiameter likewise two eccentrically extending circular arcs 6a, 6b, butthese arcs are clearcut and undercut with their branch in the proximityof the center, in order to obtain a resilient effect of these branches.Furthermore, the inner edge of each of the two free branches is beveledat an angle of approximately 45.

The function of this friction ring is as follows:

Upon forward rotation of the spindle, the ring 5 is pushed to and fro bythe cams 2a, 2b, 2c in the same manner as the locking ring 3. In thisconnection, only a quite minor friction is opposing the rotation of thetake-up spindle 2, this same friction in the devices of the prior artbeing likewise exerted against this forward movement by the locking ring3. Although there is a certain amount of friction between the cams andthe ring, this friction is even smaller in case of the friction ring 5than in case of the conventional locking ring 3, due to the resilientconstruction of the circular arcs 6a, 6b.

Upon effecting a reverse movement, one of the cams 2a, 2b, 2c meets theclosed beveled inner edge of the circular arcs 6a, 6b and first iscaught by this edge. However, the free resilient end of the respectivecircular are an be pressed toward the outside, if the force requiredtherefor is expended. The basic idea behind this embodiment is againthat the drive motor is capable of exerting the required force so that,when the camera motor is switched to reverse, a backwind of the film ispossible by overcoming the friction between the cams and the resilientfree branches of the circular arcs. However, this required amount offorce cannot be supplied by the tendency of the film windings to detachthemselves from the film reel.

The same idea likewise underlies all other embodiments. In the exampleaccording to FIG. 6, the hub of the take-up spindle 2" is covered by aclosed sleeve 7 carrying the cams 2a, 2b, 20, which latter cooperate ina conventional manner with the locking ring remaining in the cartridge.The sleeve 7 is provided with a flange 7a, by means of which the sleeverests in a recess of the take-up spindle. From the outside, a bentspring ring 8 presses against this flange, this ring resting in slots 9,9a of the take-up spindle. FIG. 7 shows the spring ring in a plan view.The function of a cartridge constructed in this manner is unchanged withrespect to the state of the art during forward movement, i.e., the cams2a, 2b, 2c push the locking ring to and fro without any large amount ofresistance. However, during reverse movement, only the sleeve 7 isactually blocked, which latter is caught with one of its cams 2a, 2b, 20at the locking ring. In contrast thereto, the take-up spindle 2" canturn backwards against the friction between the sleeve flange 7a and thespindle.

The spring ring 8 has outwardly extending projections thereon. Theseprojections are located at opposite positions on the spring ring. Thering is bent in a direction approximately at right angles to the centerline of the projections.

In the embodiment according to FIG. 8, as compared to the exampleaccording to FIG. 7, only the spring means is changed. Instead of thespring ring 8, the sleeve 10 exhibits resilient arms 10a, 10b, 100 (FIG.8) fixedly connected with the sleeve this The sleeve and the arms can,for example, be injection molded of one piece. A cover plate 11, whichis for example, cemented together with the take-up spindle, prevents thesleeve from slipping off the hub.

In the example of FIG. 10, in place of a closed sleeve, a longitudinallyslotted sleeve 12 is placed on the hub 2" of the take-up spindle. Thissleeve can be inher ently pretensioned, so that this alone effects therequited friction. However, it is also possible to surround the sleeveadditionally with a spring ring 18 supplying the required amount offriction. It is furthermore possible to insert a spring ring (not shown)between the end 12a of the sleeve and the spindle, which spring ringpresses the shoulder 12b of the sleeve, which shoulder is disposed in agroove of the hub, in the axial direction against the side wall of thehub and thus produces the friction.

In the embodiment according to FIG. 11, the sleeve 13 consists of aspring band which is ovally deformed and thus is seated on the hub 2""with pretensioning. FIG. 12 shows that the blocking cams 2a, 2b, 2c arein thic case pressed out of the sleeve 13 from the inside.

FIGS. 13 and 14 show embodiments wherein loop springs 14 and 15 areemployed for producing the friction and wherein the locking ring 3 isremoved from the cartridge. In the embodiment according to FIG. 13, the

loop spring 14 is placed over the pin 17 carrying the take-up spindle 16and is attached with one end of the hub 2""' of the take-up spindle.During forward movement, wherein, in the illustration of FIG. 13, theright side of the spindle moves out of the plane of the drawing and theleft side of the spindle enters the plane of the drawing, the loopspring is wound up so that no friction can occur between the spring andthe pin 17. During reverse movement, the loop spring 14 is, however,closed, resulting in friction at the pin. As in the remainingembodiments, this friction can, however, be readily overcome by themotor of the camera, so that a backwind of the film -is possible;however, this friction, again, cannot be overcome by the tension of thefilm, so that protection against unreeling of the film windings isachieved.

The example of FIG. 14 is effective accordng to the same principle. In amodification of the embodiment of FIG. 13, the loop spring 15 is,however, slipped over the hub 2"" of the take-up spindle 16 in thisembodiment and is attached with one of its ends at the cartridge housingproper.

We claim:

1. A film cartridge for super-8 format film including a take-up spindlemounted for forward and reverse r0- tation rotatably mounted in saidcartridge and friction means operative on said spindle to resist but notblock reverse rotation thereof, wherein the take-up spindle has aplurality of cams on the surface thereof and wherein said friction meansincludes a friction ring mounted in said cartridge and surrounding thetake-up spindle, said ring having a bore defined by two substantiallysemicircular arcs, the centers of said arcs being displaced with respectto each other in the direction to ward the ends of the semicircles, thetwo arcs having branches which are clear cut and undercut and which formtwo resilient tongues, the end of each tongue being beveled at an angleof about 45 whereby the curved path facing the cams on said spindleduring forward rotation of said spindle forms an obtuse angle with therotational path of the cams and whereby the curved path facing the camson said spindle during reverse rotation of said spindle forms an acuteangle with the rotational path of the cams.

2. A film cartridge according to claim 1, wherein said friction ring ispositioned for lateral reciprocation with respect to said spindle.

1. A film cartridge for super-8 format film including a take-up spindlemounted for forward and reverse rotation rotatably mounted in saidcartridge and friction means operative on said spindle to resist but notblock reverse rotation thereof, wherein the take-up spindle has aplurality of cams on the surface thereof and wherein said friction meansincludes a friction ring mounted in said cartridge and surrounding thetake-up spindle, said ring having a bore defined by two substantiallysemicircular arcs, the centers of said arcs being displaced with respectto each other in the direction toward the ends of the semicircles, thetwo arcs having branches which are clear cut and undercut and which formtwo resilient tongues, the end of each tongue being beveled at an angleof about 45* whereby the curved path facing the cams on said spindleduring forward rotation of said spindle forms an obtuse angle with therotational path of the cams and whereby the curved path facing the camson said spindle during reverse rotation of said spindle forms an acuteangle with the rotational path of the cams.
 2. A film cartridgeaccording to claim 1, wherein said friction ring is positioned forlateral reciprocation with respect to said spindle.